The invention relates to a pivoting device for pivotable parts of bipolar electrosurgical equipments in accordance with the preamble of claim 1.
One of the main problems during surgical interventions is rapidly and reliably stemming any bleeding which may occur. Bleeding occurs particularly during the cutting or removal of tissue by means of surgical cutting instruments. In order to achieve rapid hemostasis, there are already surgical techniques known in which the surgical scissors used to remove or cut the tissue are provided with devices for stanching bleeding. Thus, use is made in surgical interventions of f.i. bipolar electosurgical scissors whose scissor arms can be connected to a high-frequency voltage source and are suitable not only for cutting through tissue or blood vessels but also for the preferably simultaneous sealing of blood vessels by electrocoagulation. It is of course important when designing such electrosurgical scissors that the high-frequency current should flow exclusively through the desired area of tissue and that no short circuits occur between the scissor arms.
In order to ensure the necessary electrical insulation between the scissor arms of a bipolar electosurgical instrument, the proposal in the genus-forming U.S. Pat. No. 5,324,289, is to provide at least one of the two scissor surfaces which rest against one another in the closed state with an electrical insulating layer. In order furthermore also to prevent electrical short circuits via the pivoted connection between the two scissor arms, this pivoted connection is configured either as a riveted joint produced from an electrically insulating material or as a screwed joint. In this case, a screw is screwed through one scissor arm into the other scissor arm. The screw is composed of electrically insulating material, or the screw is shielded electrically from one of the two scissors arms by a sleeve composed of electrically insulating material.
U.S. Pat. No. 3,651,811 has likewise disclosed a pivoting device for the two scissor arms of a bipolar electrosurgical pair of scissors, said device comprising a screwed joint in which a screw composed of metal is electrically insulated from a scissor arm through which it is inserted by a sleeve produced from insulating material. EP-A-0 589 453 furthermore proposed a riveted pivoting device between the two scissor arms, this pivoting device likewise being decoupled electrically from the scissor arms by an insulating sleeve.
The known pivoting devices are configured in such a way that they project beyond the outer surfaces of the two scissor arms, with the result that the tissue of a patient may be damaged during an operation. With the screwed joints used, there is furthermore the risk that the screw will come loose and the fit between the two scissor arms will thus be loosened. The internal thread in one scissor arm makes the production of the scissors uneconomical. When using a riveted joint for the pivot joint of the arms of bipolar electrosurgical scissors, on the other hand, the maintenance or replacement of a defective scissor arm is difficult since it is necessary for this purpose to pry the riveted joint open. With riveted joints there is furthermore the risk that the press fit achieved between the two scissor arms will be inadequate or excessive, and this can lead to impairment of handling and of the cutting ability of the scissors.
It is an object of the invention to avoid the above-mentioned disadvantages and to propose a pivoting device for pivotable parts of bipolar electrosurgical equipments which is simple to produce and maintain and reliably prevents a short-circuiting link between the pivotable parts via their pivoting device.
This object is achieved by means of pivoting device having the features specified in claim 1. Advantageous developments of the invention are specified in the dependent claims.
According to the invention, the pivoting device for bipolar electrosurgical equipments has two electrically conductive pivotable parts, each of which is (provided with a cutting edge and which) is connected pivotably to one another by said pivoting device and those surfaces of the two pivotable parts which rest against one another being electrically insulated from one of the parts. The pivoting device is a screwed joint which comprises a screw and a nut. A hole is provided in one of the two parts for the recessed accommodation of the screw, and a further hole is provided in the other of the two parts for the recessed accommodation of a nut of the screwed joint. An electrically insulating material is provided at least in/on the surfaces of the screw and the nut and/or in/on the surfaces of the holes in the two pivotable parts.
According to a first embodiment, the nut can be provided at least in part with a smooth circumferential surface of noncircular form. The noncircular but regular smooth circumferential surface of the nut not only ensures that no twisting of the screwed joint occurs as it is tightened but also ensures an accurate fit in the hole in the pivotable part, a fit which takes account to a high degree of the hygiene requirements and virtually excludes the risk of injury or damage to body tissue or objects.
The design according to the invention of the pivoting device of the two parts of the bipolar electosurgical equipment as a screwed joint ensures reliable and precise relative seating of the pivotable parts and, hence in case of a bipolar electrochirugical scissor, a good cutting operation, since it is possible to adjust the seating of the pivotable parts or scissor arms, respectively, in an optimum manner by means of the tightening torque of the screw, and the screwed joint reliably maintains the setting, once made. The recessed arrangement of the screwed joints in the pivotable parts or scissor arms prevents unintentional injury to the tissue of the patient or catching of or damage to objects, e.g. gauze cloths or latex surgical gloves.
Since the screw and the nut of the screwed joint can be produced from the same material, the risk of undesirable wear is prevented. This can occur when the screw and nut are composed completely or in part of different materials.
A preferred solution is to provide the holes in the pivotable parts of the bipolar electrosurgical equipment in an identical and axially symmetrical manner with respect to one another with respective inner flanges.
In a second embodiment of the invention, the electrical insulation of the screwed joint of the two pivotable parts comprises a two-sleeve insert produced from electrical insulating material, this being particularly advantageous, and, in this arrangement, the inside of one sleeve being formed in positive engagement with the screw head and the inside of the other sleeve being formed in positive engagement with the nut. This configuration of the bipolar electrosurgical pair of pivotable parts likewise simplifies its product ion since the holes in the pivotable parts are of identical design, and only one tool setting is thus required. Above all, electrical insulation by means of an insert comprising two sleeves ensures a particularly high electrical breakdown strength.
As a further development of this particularly preferred embodiment, the underside of the screw head is conically tapered and rests against a correspondingly conically shaped surface of a washer, which is preferably composed of the same material as the screw. This design makes it possible to tighten the screw in a simple and reliable manner since the washer ensures good seating of the screw and prevents premature wear.
Further features and advantages of the invention are explained in greater detail with reference to the attached drawings.